Projection apparatus including means to reflect non-visible light

摘要

There is disclosed a projection apparatus 200 comprising a projector 102 which projects images onto a screen 104. The screen 104 is an active screen having modifiable optical characteristics which can be used to provide high contrast ratios in the presence of ambient light. An active portion of the screen is arranged to respond to the application of light, in particular non-visible light. The projector 102 comprises a light source 202 emitting visible light which passes through a colour wheel 204 before impinging on a digital minor device (DMD) 208. In a first (ON) position the visible light is reflected by the DMD towards screen 104 where it illuminates a pixel region 218. In a second (OFF) position the visible light is reflected by the DMD to a light dump 212. The projector also comprises a non-visible light source 214 which may emit UV or IR light towards the DMD 208. In the ON position the non-visible light is reflected by the DMD towards light dump 222, in the OFF position the non-visible light is reflected by the DMD towards screen 104 where it causes an active portion of the screen to assume a particular optical characteristic. This projector arrangement may be used to provide a projected image having improved contrast or reduced glare in ambient light conditions.